Polar codes attract more and more attention of researchers in recent years, since its capacity achieving property. However, their error-correction performance under successive cancellation (SC) decoding is inferior to other modern channel codes at short or moderate blocklengths. SC-Flip (SCF) decoding algorithm shows higher performance than SC decoding by identifying possibly erroneous decisions made in initial SC decoding and flipping them in the sequential decoding attempts. However, it performs not well when there are more than one erroneous decisions in a codeword. In this paper, we propose a path metric aided bit-flipping decoding algorithm to identify and correct more errors efficiently. In this algorithm, the bit-flipping list is generated based on both log likelihood ratio (LLR) based path metric and bit-flipping metric. The path metric is used to verify the effectiveness of bit-flipping. In order to reduce the decoding latency and computational complexity, its corresponding pipeline architecture is designed. By applying these decoding algorithm and pipeline architecture, an improvement on error-correction performance can be got up to 0.25dB compared with SCF decoding at frame error rate of 10 −4 , with low average decoding latency.

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Polar codes have drawn much research attention in the last ten years for their capacity-achieving property. However, their conventional successive cancellation decoding method performs not well at a short or moderate length. In order to improve the performance, concatenation with other error-correction codes has been proved an effective approach, whereas current concatenation schemes using rate-optimized method are too complex to implement with long decoding latency. In this paper, we propose a critical set protected BCH-Polar code with its corresponding decoding architecture. In the proposed concatenation scheme, we only provide extra protection to partial information bits in the critical set, which is constructed based on the channel reliability. For its corresponding decoding architecture, we redesign some components and adopt the Look-up table decoding method for BCH codes, resulting in much degradation of decoding latency. Compared with existing decoders, the hardware implementation shows low decoding latency and high throughput-area efficiency. INDEX TERMS Concatenated polar codes, low latency, critical set, successive cancellation decoding, BCH codes.

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